BoilerFaultCodes.com
h Low Information

Your boiler is currently running at its maximum power to heat your radiators and it is not a fault, but an indication of high demand.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Burner on with maximum CH power setting

What causes this fault?

This status appears when you first turn your heating on or if there has been a significant drop in temperature in your home. It occurs because the boiler has been instructed to run at its highest possible power output to reach your desired thermostat setting as quickly as possible. Once the rooms begin to warm up, the boiler will naturally reduce its power and the code will disappear.

This code is most frequently seen during the first cold snaps of autumn and winter when the heating system is working hardest to warm up a cold building.

Typical repair cost £0 (including labour)

DIY fix possible

Check if your room thermostat or TRVs are set to a very high temperatureWait for the house to warm up to see if the status code changes once your home reaches the target temperatureMonitor the boiler to ensure it eventually settles into a lower power state (indicated by a different number)

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Protect yourself from future repair bills

A boiler cover plan would cover faults like h — no call-out fees, no surprises.

Top rated
OpenFix
Boiler & heating care plans
Get a quote →
Hometree
from £12.95/month
Get a quote →
HomeServe
from £8.00/month
Get a quote →

Affiliate links — we may earn a commission at no extra cost to you.

Related fault codes